An Introduction to the Appendicular

Skeleton

The Appendicular

Skeleton is composed

of the 126 bones of the

appendages (limbs)

and the pectoral and

pelvic girdles, which

attach to the axial

skeleton.

Each limb is composed

of three segments

connected by freely

movable joints.

Identify bone markings of each bone. The

markings will help you to determine

whether a bone is the right or left member

The Pectoral Girdle

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The pectoral girdle, also called the shoulder

girdle consists of two clavicles two scapula.

The pectoral girdle connects the arms to the

axial skeleton

Provides arm movement and shoulder

movement.

The Clavicles

The Clavicles, called collarbones, are long, S-shaped bones.

It’s medial end attaches to the sternal manubrium (sternal

end). This articulation is called the sternoclavicular joint. This

is the only bony attachment between the upper extremity and

the axial skeleton.

The lateral end is flattened and articulates with the scapulae

(acromial end) to form part of the shoulder. This articulation is

called the acromioclavicular joint.

The clavicle serves as a brace, or strut, to

hold the arm away from the top of the

thorax.

The Scapulae

The Scapulae or shoulder blade are broad, flat

triangles. They have two important processes: the

acromion and coracoid process.

The acromion connects with the clavicle.

The beaklike coracoid (corac = crow, raven) process points

anteriorly over the tip of the shoulder joint and anchors some

of the upper limb muscles. The scapula has no direct

attachment to the axial skeleton.

The scapula has 3 angles: superior, inferior,

and lateral and 3 named borders: superior,

medial, and lateral.

Notice the spine of the scapula, located on the

posterior.

There are several fossae (shallow depressions) that

appear on both sides of the scapula and are named

according to location.

The glenoid cavity, a shallow socket

articulates the humerus head of the arm

bone.

The Arm

The humerus (the

brachium) consists of the

only bone in the arm. It is

involved in the formation

of 2 major joints: the

shoulder and the elbow

joint.

The humerus head fits

into the shallow glenoid

cavity. The greater

(lateral) and lesser

(medial), turbercles are

separated by a groove,

the intertubercular

sulcus that guides the

tendon of the bicep

muscle to the glenoid

cavity.

The posterior

view of the

humerus has a

roughened

area, the

deltoid

tuberosity,

where the

shoulder deltoid

muscle

attaches.

The distal end of the

humerus are the medial

trochlea (looking rather

like a spool), which

articulates with the ulna.

The lateral capitulum

articulates with the radius

of the forearm.

The condyles are flanked

by the medial and lateral

epicondyles.

Above the trochlea is the coronoid fossa on the

anterior surface. The posterior surface is the

olecranon fossa. The depressions allow the ulna to

flex and extend.

The Forearm

The Forearm (also called

the antebrachium)

consists of two long

bones: the Ulna (medial)

and the Radius (lateral).

In the anatomical

position the radius is in

the lateral and the ulna is

in the medial position.

They are joined by an

interosseous membrane.

The Radius disk-

shaped head

articulates with the

capitulum of the

humerus.

Just below the head is

the Radial tuberosity

where the tendon of

the biceps muscle of

the arm attaches.

The lateral aspect of its

distal end is the

expanded styloid process.

Palpatate the syloid

process (thumb side),

move your fingers just

medially onto the anterior

wrist. Press firmly and

then let up slightly on the

pressure. You should feel

your radial pulse.

The Ulna the medial bone of the forearm. Its proximal end

bears the anterior coronoid process and the posterior

olecranon process (the point of the elbow), which are

separated by the trochlear notch.

The Hand

The skeleton of the hand includes 3 groups of bones: the

carpals (wrist bones), metacarpals (bones of the palm), and

phalanges (bones of the fingers).

The carpus (the wrist) is arranged in 2 irregular rows

of four bones each. The bones are bound by

ligaments. The 4 proximal bones:

Scaphoid: Near styloid process, Lunate: Medial to scaphoid,

Triquetrum: Medial to lunate bone, Pisiform: Anterior to

triquetrum

The Four Distal Carpal Bones:

Trapezium: Lateral, Trapezoid: Medial to

trapezium, Capitate: Largest, Hamate: Medial,

distal

The Metacarpal Bones, numbered 1 to 5 from the thumb side of the hand, radiate out from the wrist like spokes to form the palm of the hand.

They articulate with proximal phalanges.

Clench your fist and find the knuckles, these are your metacarpophalageal joints.

Phalanges, mini long bones of the hands, (14 total finger bones). Like the bones of the palm, the fingers are numbered from 1 to 5, beginning from the thumb side of the hand.

Each finger has 3 phalanges (proximal, middle, distal), except the thumb (pollex) which has 2 (proximal & distal).